This invention relates generally to instruments designed for accessing body cavities. More specifically, this invention relates to an adapter for a laparoscopy cannula and assembly.
Cannula assemblies traditionally have been used in laparoscopic surgery for several decades. In laparoscopy, a small incision is required to access an area where a wide range of surgical procedures can be performed with minimal traumna to the tissues. Until the invention described in this inventor""s prior U.S. Pat. No. 5,478,329 and its division, U.S. Pat. No. 5,630,805, the disclosures of which are incorporated herein by reference, a surgeon would use a trocar assembly to gain access to the peritoneal cavity during a laparoscopic procedure. The trocar assembly included a trocar (also called an obturator) and a cannula, a tube through which the trocar is guided. Because the cannula end is blunt, in order to access the peritoneal cavity, the trocar would be used to pierce the layers of the anterior abdominal wall.
One such prior art trocar assembly is disclosed in U.S. Pat. No. 5,226,890. This trocar assembly includes a tissue engaging member, a guide tube member, and a collet for locking the tubular guide member to the externally smooth cannula. The conical tissue engager is helically threaded on its external surface so that it can be rotated into an incision to engage the tissue. Once the tissue engager is positioned, the trocar cannula is inserted into the bore of the tissue engager and is locked into place using the collet.
The principal disadvantage of using such a trocar assembly is that significant initial axial force is required to insert the trocar blindly through the layers of the anterior abdominal wall, transecting tissue along the way into the body cavity and increasing the possibility of the trocar being inadvertently inserted further into the abdominal cavity than is necessary or desirable, which could result in injury to major blood vessels or to other visceral organs.
The method and apparatus disclosed in U.S. Pat. Nos. 5,478,329 and 5,630,805 obviate such disadvantages. In a non-limiting embodiment, these patents disclose a trocarless cannula and a visual method for accessing a body cavity using such a trocarless cannula. Rather than the blunt-ended cannula of the then-prior art, the distal end of the trocarless cannula has a tip construction which incrementally and sequentially parts different tissue layers radially under vision along the port tract. The outer surface of the trocarless cannula includes a screw thread or groove which allows the cannula, after insertion via a small incision, to enter the body cavity, while maintaining a seal between the cannula body and the incision.
Therefore, a need has arisen for an improved trocarless cannula assembly which is able to better stabilize and hold the cannula in place. Such an improved trocarless cannula assembly should also improve and maintain an airtight seal between the cannula and the port site. And, as an added benefit, such an improved trocarless cannula assembly should also be able to steadily increase the size of the principal port into the body without transecting the tissues at port site, especially when a large surgical specimen needs to be removed.
To meet this need, the present invention provides an adapter for use on an external surface of a laparoscopy cannula, wherein the adapter, having a proximal end and a distal end, comprises a generally tubular body having an outer surface for radial spreading of a body entrance opening and snugly engaging body tissue, and an inner surface for grasping the internal surface of the cannula. The present invention further provides an adapter comprising a generally tubular body having a proximal end, a distal end, and an inner surface forming a lumen within the body extending throughout its entire length, an outer surface, and means on the inner surface of the adapter body for grasping the external surface of the cannula, wherein the proximal end of the adapter body has a larger diameter than the distal end of the adapter body to aid in radial spreading of a body entrance opening.
The adapter further comprises a means on the outer surface of the adapter body for snugly engaging body tissue. For example, a means of doing this is for the adapter body to have one or more helical thread(s) or groove(s) of a fixed or variable pitch on the outer surface. The adapter body preferably is tapered in its diameter from the proximal end to the distal end. One embodiment of this taper is for the adapter body to be substantially conically shaped. It is also preferable for the outside diameter at the distal end to approach the outside diameter of the cannula. The adapter may optionally include a suture holding mechanism to secure a suture to the patient""s body. The suture holding mechanism may be a notch in the adapter body, or an arm or rod attached to the adapter body. An adapter in accordance with the present invention can be part of an open or closed laparoscopy cannula assembly.
A variety of means on the inner surface of the adapter body for grasping the external surface of the cannula are contemplated that coapt with the external surface of the cannula. The external surface of the cannula may be smooth, threaded or grooved and fabricated from single or multiple use materials. The inventive adapter may be fabricated from traditional single or multiple use materials, or may be fabricated in whole or in part from an elastomeric material that snugly engages the external surface of the cannula. The internal surface of the inventive adapter may be smooth, threaded or grooved.
For adapters fabricated of traditional single or multiple use materials, the means on the inner surface of the adapter body for grasping the external surface of the cannula would depend upon the external configuration of the cannula. For example, a cannula having an external helical thread would require an adapter body having a coapting inner helical groove, and a cannula having an external helical groove would require an adapter body having an inner helical thread.
For adapters fabricated in whole or in part from an elastomeric material that snugly engages the external surface of a cannula in accordance with the present invention, the means for grasping on the inner surface of the adapter body may be configured to coapt with the external surface of the cannula, or may be designed to coapt with any configuration of the external surface of the cannula. For example, an adapter having an elastomeric inner surface may be designed having a helical thread that coapts with an external helical groove of the cannula and an adapter having an elastomeric inner surface may be designed having a helical groove that coapts with an external helical thread of the cannula. Further, the adapter having an elastomeric inner surface may be designed with a smooth inner surface that is capable of firmly grasping the external surface of a smooth, threaded or grooved cannula because of the elasticity of the deformable elastomeric material.
Alternatively, the external surface of the laparoscopy cannula may comprise an elastomeric material, wherein the elastomeric material has a helical thread or groove that is designed to coapt with a helical groove or thread of a laparoscopy cannula adapter. Further, the elastomeric outer surface of the cannula may be designed with a smooth outer surface that is capable of grasping a smooth, threaded or grooved internal surface of a laparoscopy cannula adapter.
The present invention further provides for a laparoscopy cannula adapter assembly comprising a laparoscopy cannula having an external surface and an adapter comprising a generally tubular body having an outer surface for aiding in radial spreading of a body entrance opening and snugly engaging body tissue, and an inner surface of said body for grasping the external surface of the cannula.
The cannula or adapter may be made entirely of the elastomeric material contemplated by the present invention or may be applied as a surface coating on the cannula or adapter, and may be threaded, grooved, smooth or may have protruding nubs of elastomer.
The invention is further directed to a method for aiding in the radial spreading of a body entrance opening during laparoscopy to facilitate removal of large surgical specimen without having to transect tissues along the port tract, the method comprising accessing the peritoneal cavity through the body entrance opening using a cannula and winding an adapter that grasps the external surface of the cannula as it winds down the cannula until the adapter lodges into the body entrance opening, wherein the body entrance opening is radially spread by the external surface of the adapter body.
Also in accordance with the present invention is a method of maintaining the position of a cannula during laparoscopy, the method comprising accessing the peritoneal cavity through the body entrance opening using a cannula, positioning the cannula at a desired depth inside the body entrance, winding an adapter that grasps the external surface of the cannula as it winds down the cannula until the adapter body lodges into the body entrance opening, and radially spreading the body tissue at the body entrance, wherein the engagement between the body tissue, the adapter, and the cannula maintains the position of the cannula during laparoscopy.